Currently, in the field of wireless networks, the wireless local area network (WLAN in short) develops rapidly, and the demand on WEAN coverage in the world is increasing. The industrial specification 802.11 work group of Institute for Electrical and Electronic Engineers (IEEE in short) defined a series of WLAN technology standards such as 802.11a, 802.11b, 802.11g and so on, which mainly specified physical layer protocol (PHY in short) and media access control (MAC in short) layer specifications. Other task groups appear in the following which are dedicated to developing specifications involving existing 802.11 technology improvements, for example, the 802.11ab task group mainly involves the utilization of resources of permit-free hands below 1 GHz band, for supporting new applications such as intelligent grid, sensor network and cellular network load balance and so on.
When formulating the technology specifications thereof, the 802.11ah wishes that the technology specifications of 802.11ab follow the technology specifications of the existing 802.11 as much as possible, and at the same time in order to meet the special attributes of 802.11ah itself, also makes proper modifications or formulates new technology specifications regarding the existing technology specifications. Currently, the 802.11ah task group determines that the operating bandwidth of the technology can be 1/2/418/16 MHz, the orthogonal frequency division multiplexing (OFDM in short) modulation technology is employed, the duration of each OFDM symbol (containing a long protection interval) is 40 μs, which is 10 times expanded relative to the duration of each OFDM symbol in the existing 802.11 series standards. In other words, for sending the same information, the energy consumption of the device which employs 802.11ah technology specifications will be 10 times of that of the device which meets the existing 802.11 technology specifications, however, the device which meets the 802.11ah technology specifications has relatively high requirements in terms of energy saving, which thus requires to complete corresponding functions in a shorter information transmission manner.
In the existing 802.11 technology specifications, the basic network architecture thereof is that one access point (AP in short) and a plurality of non-AP stations (STA in short) associated with the AP form a basic service set (BSS in short), and each basic service set has a basic service set identifier (BSSID in short). When performing closed loop multi-antenna transmission, such as Beamforming transmission, the initiator Beamformer has to learn the channel information between itself and the receiver Beamformee, then it requires the Beamformee to perform channel measurement and feed the channel measurement information back to the Beamformer. If the Beamformee does not perform feedback immediately after performing channel measurement, or an error occurs in the channel measurement feedback information received by the Beamformer, then the Beamformer will send a beamforming report poll frame to request the Beamformee to feed back all the channel measurement information or the portion of channel measurement information which is not received by the Beamformer correctly. The format of the current beamforming report poll frame is as shown in FIG. 1, it can be seen from FIG. 1 that there are few loads on the MAC frame of the beamforming report poll frame, and the MAC frame may be re-designed, and the functions thereof may be completed with fewer resources.
In the existing 802.11 technology specifications, the signal field in the physical layer header of a radio frame usually contains a LENGTH/DURATION sub-field, an STBC sub-field, a modulation and coding scheme (MCS in short) sub-field, a coding type sub-field, a cyclic redundancy code (CRC) sub-field and a reserved bit sub-field and so on. The signal field is referred to as common signal field here and is usually followed by a physical frame load, and the information of some subfields in the signal field is usually corresponding to the physical frame load, such as MCS subfield, for indicating the modulation and coding scheme used by the load on the physical frame, if a radio frame does not carry a physical layer load, then some subfields, such as MCS subfield, in the signal field of the physical layer header has no meaning.